Electric boards,plug contacts and system



June 24, 1969 s. T. DEAKIN ELECTRIC BOARDS, PLUG CONTACTS AND SYSTEMSheet Filed July 6. 1966 INVENTOR. STANLEY THOMAS 054/0 June 24, 1969 s,DEAK|N Q 3,452,315

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STANLEY THOMAS 0154/0 Wwgm United States Patent 3,452,315 ELECTRICBOARDS, PLUG CONTACTS AND SYSTEM Stanley Thomas Deakin, Fariington,Sealectro Limited, Farlington, company Filed July Claims priority,

England, assignor to England, a British 6, 1966, Ser. No. 563,279

application Great Britain, July 6, 1965,

Int. Cl. H01r 25/02, 11/22 US. Cl. 33918 7 Claims ABSTRACT OF THEDISCLOSURE The invention relates to electric boards, plug contacts andplug board systems and is concerned with apparatus for making electricalconnection between two (or more) co-axial socket contacts in a selectorboard containing a multiplicity of such sockets. Plug contacts have beenused, for example, with selector boards such as that disclosed inBritish patent specification No. 934,627 in which there are two sets ofsocket contacts in pairs one above the other, the plug contacts beinginserted in selected pairs to eifect electrical connections between thetwo members of each selected pair. It is an advantage of the presentinvention that, unlike the construction disclosed in British patentspecification No. 934,627, the socket contacts shall be withoutresilience (e.g. in the form of tubular eyelets) and that the resiliencenecessary to ensure eifective connection is provided by the plugcontact. In that case a problem which arises is that of ensuring thatthe plug contact makes proper engagement with both of the socketcontacts which may, for example, be slightly out of line or differslightly in size. The invention seeks to overcome or reduce thisproblem.

The invention provides an electric plug contact for the above purposewhich comprises at least two plug portions integrally connected by aneck, the plug portions having independent radial resilience.

In one form of the invention the contact is of generally tubular formthreaded (e.g. loosely) over a carrier stem. The contact may be held onthe stem between two enlargements of the stem, of which one may providea tapered nose for leading the contact into the sockets and the othermay provide a finger grip for manipulating the contact.

Among the many advantages of this plug board system is that it enablesthe use of strong, rigid socket eyelets having long life, and in theevent that the resilient contacts become displaced, it is the individualplug, not the whole selector board, which is replaced.

In a preferred construction the contact is in the form of a tube ofgenerally triangular section split along the edge provided by an apex ofthe triangle and divided into two (or more) plug portions axiallyseparate from one another except for an interconnecting neck at the sideopposite to the said edge.

3,452,315 Patented June 24, 1969 Two specific constructions of plugsembodying the invention will now be described, by way of example, withreference to the accompanying drawings in which:

FIGURE 1 is a section through one of the plugs,

FIGURE 2 is a perspective view of the plug contact,

FIGURE 3 shows a blank from which the plug contact is formed,

FIGURE 4 is a perspective view of the contact of the second plug,

FIGURE 5 shows a carrier and finger grip for the second plug,

FIGURE 6 shows part of a selector board with which the plugs may beused, and

FIGURE 7 shows a selector board system including a plurality of decks ofrigid socket contacts interconnected by insertion of the plugs.

The plug shown in FIGURES 1-3 comprises a metallic tubular plug contact10 loosely threaded over a carrier stem 11 which may be of metal orinsulating material. The stem has a tapered nose 12 and a finger grip 13which provide enlargements holding the contact 10 in place. The contactmay be sprung into place over the head or formed around the stem.

The contact is formed by rolling up a blank of the form shown in FIGURE3 to the generally triangular section tubular form seen in FIGURE 2.This consists of two independently resilient portions 15, 16 joined by anarrow neck 17 and divided at 18 along an apex of the triangularsection. The gap at 18 enables each portion to compress resilientlyindependently of the other portion.

The plug shown in FIGURES 4 and 5 has a contact (FIGURE 4) formed bybending a blank of sheet or strip resilient metal (e.g. berylliumcopper) to tubular form 19 leaving an opening or gap 20, with two pairsof cars 21, 22 reversely bent from the edges of the opening to overliethe outside of the tubular portion but slightly spaced therefrom. Theears extend round to the back of the tube to leave gaps between the earsof a Width about equal to that of the gap- 20. Each pair of earsprovides resilient contact surfaces or plug portions for engagement in asocket and may be compressed without substantial deformation of the tubeand independently of the other pair. The tube 19 constitutes a neckjoining the two plug portions. The lower end of the tubular portion isdomed at 23 to provide a lead in and the upper end is notched at 25 toreceive and hold a projection 26 on an insulating stern on a finger grip27 (FIGURE 5) when the stem is inserted in the tubular portion.

In use of either of the above plug constructions the contact is insertedinto one pair of sockets, e.g. the pair seen at 40, 41 in FIGURE 6, of aselector board so that the two portions 15, 16 or 21, 22, make contactwith the two sockets 41, 40 respectively and the plug effects electricalconnection between the two sockets.

The sockets are provided by rows of rigid eyelets, which areinterconnected by connection strips 46 and 47 to form sets of rows, therows being at right angles, attached to insulating plates 43, 44 to formrespective decks of socket contacts which are separated by an insulatingplate 45.

FIGURE 7 illustrates the operation of the plug board system enablinggood electrical connection to be provided between the rigid socketcontacts in the respective decks regardless of whether the co-axialsocket contacts may be slightly out of line or differ slightly in size.

The invention is not restricted to the details of the above examples.For instance the contact of FIGURE 4 may be fitted over a carrier sternsimilar to that of FIGURE 1, the domed end 23 being omitted.

I claim:

1. An electric plug adapted to be inserted into a plurality of co-axialsockets, said plug comprising a stem carrying at least two resilientplug contact portions for engaging the respective sockets, said contactportions comprising a split tube divided circumferentially to form atleast two plug contact portions axially separate from one another exceptfor a narrow interconnecting neck, the tubular contact portions beingthreaded onto the carrier stem and being radially spaced therefromwhereby the plug contact portions have independent radial resilience,said tube being of generally triangular configuration having roundedapexes as seen in cross section, said tube being split along an edgecorresponding to an apex of the triangular section, the neckinterconnecting the plug contact portions or adjacent plug contactportions, being at the side of the triangular section opposite to thesaid split edge.

2. A plug as claimed in claim 1 in which the carrier stem is made ofinsulating material. 4

3. A plug as claimed in claim 2 in which the plug contact portions areheld on the carrier stern between two enlargements of the stem.

4. A plug as claimed in claim 3 in which one enlargement provides atapered nose for leading the adjacent plug contact portion into a socketand the other provides a finger grip for manipulating the plug. 5. Aselector board system comprising a plurality of decks each containing amultiplicity of rigid socket contacts interconnected in sets of rows,the socket contacts in one of said decks being in co-axial relationshipwith and being insulated from the socket contacts in another of saiddecks with the sets of rows on one deck relatively crossing the sets ofrows on the other deck, and at least one electric plug inserted intoco-axial socket contacts in both of said decks electricallyinterconnecting the respective sockets, said plug having a finger gripwith a carrier stem extending therefrom and carrying at least two spacedresilient plug contact portions, said contact portions comprising a tubesaid tube being divided circumferentially to form at least two plugcontact portions axially spaced one from another joined by a narrowinterconnecting neck extending in an axial direction between said plugcontact portions, said tube being of generally triangular configurationhaving rounded apexes as seen in cross section, said tube being splitalong an edge corresponding to an apex of the triangular section, theneck interconnecting the plug contact portions or adjacent plug contactportions, being at the side of the triangular section opposite to thesaid split edge, said plug contact portions having independent radialresilience for engaging the respective sockets, and said plug contactportions being threaded loosely onto said carrier stem and being spacedradially therefrom, whereby said plug contact portions carried by saidstem have independent radial resilience for said apexes to engage therespective sockets of the selector board.

6. An electric plug inserted into a selector board, said selector boardhaving two superposed crossing sets of rows of interconnected socketeyelets, the plug being inserted into an eyelet of each set at aposition of crossing of a row of each set, said plug comprising a sterncarrying at least two resilient plug contact portions en- .4 gaging therespective sockets of the selector board, said contact portionscomprising a split tube divided circumferentially to form at least twoplug contact portions axially separate from one another except for anarrow interconnecting neck, the tubular contact portions being threadedonto the carrier stern and being radially spaced therefrom whereby theplug contact portions have independent radial resilience, said tubebeing of generally triangular configuration having rounded apexes asseen in cross section, said tube being split along an edge correspondingto an apex of the triangular section, the neck interconnecting the plugcontact portions or adjacent plug contact portions, being at the side ofthe triangular section opposite to the said split edge.

7. An electric plug adapted to be inserted into spaced co-axial socketsin a selector board, 'said sockets being located one behind another andsaid plug being adapted for providing electrical contact between therespective co-axial sockets, said plug comprising a finger grip with acarrier stem extending therefrom and carrying at least two spacedresilient plug contact portions, said contact portions comprising a tubehaving a gap extending axially along one side thereof, said tube beingdivided circumferentially to form at least two plug contact portionsaxially spaced one from another joined by a narrow interconnecting neckextending in an axial direction between said plug contact portions saidplug contact portions having independent radial resilience, and saidplug contact portions being threaded loosely onto said carrier stem;said carrier stern having an enlarged tapered nose thereon at the frontend thereof providing an enlargement for holding said plug contactportions thereon, said plug contact portions being spacedradiallytherefrom and having a plurality of apexes extending outwardlyfurther from said stem, whereby said plug contact portions carried bysaid stern have independent radial resilience for engaging therespective sockets of the selector board ensuring that the plug contactmakes proper engagement with the respective socket contacts regardlessof whether the socket contacts may be slightly out of line.

References Cited UNITED STATES PATENTS Great Britain. Great Britain.

MARVIN A. CHAMPION, Primary Examiner.

US. Cl. X.R. 339252

